Stereoscopic percutaneous visualization system

ABSTRACT

A surgical microscope comprising a microscope body, lens means attached to the microscope body for magnifying an object image, an eyepiece attached to the microscope body for viewing the magnified object image, and coupling means attached to the microscope body for retaining a supplementary lens in optical alignment with the lens means, the coupling means being configured for introducing the supplementary lens through a percutaneous penetration into a body cavity, wherein the eyepiece and the lens means are configured to facilitate stereoscopic viewing. In a variation of the surgical microscope, a plurality of binocular eyepieces are attached to the microscope body to allow multiple persons to contemporaneously view the magnified object image.

CROSS-REFERENCE TO RELATED APPLICATION

This is a continuation of U.S. patent application Ser. No. 08/612,810filed on Mar. 11, 1996, now issued as U.S. Pat. No. 5,957,832, which isa division of application Ser. No. 08/227,366, filed Apr. 13, 1994, nowissued as U.S. Pat. No. 5,588,949, which is a continuation-in-part ofU.S. patent application Ser. No. 08/135,387, filed Oct. 8, 1993, nowabandoned, the complete disclosures of which are incorporated herein byreference.

FIELD OF THE INVENTION

This invention relates generally to surgical instruments for use inminimally-invasive surgical procedures such as endoscopy, thoracoscopy,laparoscopy, pelviscopy, and arthroscopy. More specifically, theinvention relates to percutaneous visualization systems for use in suchminimally-invasive surgical procedures.

BACKGROUND OF THE INVENTION

In minimally-invasive surgical techniques such as endoscopy,thoracoscopy, laparoscopy, pelviscopy, arthroscopy, and the like,elongated instruments are introduced into the body through smallincisions or percutaneous cannulae to perform surgical procedures at aninternal site, obviating the need for the large incisions characteristicof conventional, open surgical techniques. Visualization is facilitatedby the use of specialized devices known as endoscopes, laparoscopes,pelviscopes, thoracoscopes, or arthroscopes, which typically consist ofa rigid, elongated tube containing a lens system and, at the proximalend of the tube, an eyepiece or camera mount. The distal end of the tubeis introduced into the body through an incision or cannula, and, bylooking through the eyepiece, a surgeon may observe the interior of abody cavity. In addition, a small video camera may be attached to thecamera mount and connected to a video monitor to provide a video imageof the procedure. Usually, such visualization devices further include alight source at the distal end of the tube for illuminating the interiorof the body cavity.

As the complexity of the procedures that can be performed by means ofminimally-invasive techniques has increased, so has the demand forhigher quality visualization systems to facilitate such procedures. Forexample, in commonly-assigned co-pending application Ser. No.08/023,778, filed Feb. 22, 1993, the complete disclosure of which isincorporated herein by reference, new techniques are disclosed forperforming coronary artery bypass grafting and other thoracic surgicalprocedures using minimally-invasive techniques. Coronary artery bypassgrafting involves the use of microsurgical techniques to create ananastomosis, usually by suturing, between a coronary artery and eitheran existing artery such as the mammary artery, or a natural or syntheticarterial shunt connected to an upstream arterial blood source. Asdescribed in the forementioned patent application, long-handledmicrosurgical tools may be introduced through small incisions orcannulae positioned in the intercostal spaces of the rib cage to performthe anastomosis. Such procedures may take a team of surgeons up toseveral hours to complete. These intricate procedures therefore demand avisualization system that produces an extremely high-quality image ofvery small surgical sites, and that allows multiple surgeons tosimultaneously view a surgical site comfortably over long periods oftime.

While many of the visualization devices in current use have proven to beeffective for use in certain minimally-invasive surgical procedures,such devices are frequently inadequate for the performance of complexmicrosurgical procedures such as coronary artery bypass grafting. Forexample, if just an eyepiece is used on an endoscope, only one personcan look through the device at any one time, requiring an individualscope introduced through a separate incision or cannula for each personassisting in or observing the procedure. Further problematic is thedifficulty in maintaining the eyepiece in alignment with the surgeon'seye for continual visualization while manipulating the instrumentsnecessary to perform the procedure. Additionally, because thesevisualization devices are typically monoscopic, they have poorresolution of depth of field in comparison to a person's binocular,stereoscopic vision using both eyes.

By mounting a video camera on such visualization devices, more than oneperson may observe a procedure by watching a video monitor, without theneed for additional incisions into the body cavity. However, theminiature video cameras in current use frequently produce sub-optimalimage quality in comparison to direct vision through the scope. Further,indirect visualization by means of a video monitor rather than by directsight is somewhat disorienting, and requires significant training andpractice to develop the hand-eye coordination necessary to adeptlyperform surgery. Additionally, where multiple surgeons are working inthe surgical site under video imaging by a single scope, the video imagecan be correctly oriented relative to only one of the surgeons at anytime. Other surgeons must adjust their actions to compensate for aninverted or otherwise misoriented image. Moreover, because most scopes,video electronics, and video displays in current use are monoscopic,video visualization also fails to provide the depth perception of normalstereoscopic vision.

What is needed, therefore, is a percutaneous visualization system foruse in minimally-invasive surgical procedures that facilitates direct,stereoscopic visualization of a body cavity through a small incision orcannula. The visualization system should facilitate hand-eyecoordination that is close or equal to that of open surgical procedures.Preferably, the visualization system will have the capability forwide-angle visualization as well as magnification to facilitate theperformance of complex microsurgical procedures. Further, thevisualization system should allow multiple surgeons to simultaneouslyview the same surgical site with comfort for long periods of time. Thevisualization system will preferably be configured for introductionthrough intercostal spaces of the rib cage for thoracoscopic procedures,but should be useful in any of a variety of minimally-invasiveprocedures, including laparoscopy, pelviscopy, arthroscopy and the like.

SUMMARY OF THE INVENTION

The invention provides a percutaneous visualization system and methodthat facilitate direct, stereoscopic visualization of a body cavity. Thevisualization system has both wide angle and magnification capabilitiesand produces extremely high image quality, thereby facilitating theperformance of intricate microsurgical procedures usingminimally-invasive techniques. Using the system and method of theinvention, multiple surgeons may simultaneously view a surgical sitecomfortably for extended periods. The visualization system also allowsvarious lenses to be easily interchanged or combined to optimize focallength and field of view. The system may further include a light sourceto illuminate the body cavity, as well as a passage for introduction ofinstruments into the body cavity. The system is particularlywell-adapted for use in thoracoscopic procedures by positioning inintercostal spaces of the rib cage, but is also useful in endoscopic,laparoscopic, pelviscopic, arthroscopic, and other minimally-invasiveprocedures.

The visualization system of the invention includes a tubular cannulasuitable for percutaneous introduction into a body cavity such as thethorax, abdomen, pelvis, cranium, or joint cavity. The cannula has anoptical passage extending from its proximal end to its distal end thatis configured to allow stereoscopic visualization of the body cavity. Ina preferred embodiment, at least a portion of the optical passage istapered toward the distal end at a taper angle selected to facilitatestereoscopic visualization of the body cavity through the opticalpassage. Usually, the taper angle of the optical passage will be atleast 5° and less than 45°, and preferably between 5° and 20°.

In one embodiment, the optical passage is open from the proximal end tothe distal end to allow surgical instruments, sutures, prostheses,tissue, light or light sources, visualization devices, and the like, topass through the optical passage into or out of the body cavity.Alternatively, the cannula may include lens means mounted in the opticalpassage. The lens means preferably comprises a wide-angle lens system,such as a negative focal length lens, and may be permanently fixed orremovably mounted in the optical passage. Such a lens means facilitatesviewing a field within the body cavity which is substantially largerthan the penetration through which the cannula is introduced—that is,substantially larger than the transverse cross-sectional area of thecannula itself. In a preferred embodiment, the lens means is mounted ina sleeve which is configured to be removably positioned in the opticalpassage. Where the optical passage is tapered, the sleeve iscorrespondingly tapered so as to nest within the cannula. In this way,the user may look directly through the optical passage in the cannulainto the body cavity, or position a sleeve with wide-angle lens in thecannula to widen the field of view. Multiple sleeves with various lensesmay be interchanged as the user desires.

The visualization system may further include magnification means that isoptically alignable with the optical passage in the cannula. Themagnification means preferably comprises a stereo-microscopepositionable in alignment with the optical passage proximal to thecannula's proximal end. In a preferred embodiment, the stereo-microscopehas a plurality of binocular eyepieces to allow multiple persons to viewthe surgical site simultaneously through the optical passage in thecannula. The use of a high-power stereo-microscope produces extremelyhigh image quality at selectable magnification, thereby facilitatingvisualization of intricate microsurgical procedures. Alternatively, themagnification means may comprise binocular surgical telescopes, or“loupes,” worn on the head of the user, much like eyeglasses withmagnifying lenses.

The cannula is preferably configured for percutaneous introductionthrough an intercostal space in the rib cage into the thoracic cavity.The cannula may also be introduced into the abdominal cavity or into thepelvis. To facilitate introduction, the visualization system may furtherinclude an obturator or trocar that is positionable in the opticalpassage in the cannula. The obturator may have a sharpened or roundedtip that extends distally from the distal end of the cannula topenetrate tissue. Once the cannula has been positioned with its distalend in the body cavity, the obturator is removed.

The system may further include means for maintaining the cannula in aparticular position or orientation relative to the patient's body. In apreferred embodiment, the means for maintaining the position of thecannula comprises a support structure that is fixed to the operatingtable supporting the patient, and a pivotable clamp attached to thesupport structure which may be clamped to the visualization cannula. Inthis way, the cannula may be positioned as desired and locked in placewith the clamp. Alternatively, the cannula may be secured to the body ofthe patient, to the surgical drapes, to the surgical microscope, or toother supporting structures.

In a particularly preferred embodiment, the cannula of the invention iscoupled directly to the microscope, thereby maintaining alignmentbetween the two and securing the cannula in position. To facilitateinterchanging lenses without decoupling the cannula from the microscope,an aperture may be provided in a side of the cannula in communicationwith the optical passage to allow lenses to be interchanged through theaperture. Alternatively, the sleeve which holds the lens means may becoupled to the microscope, the cannula remaining separate so that it maybe positioned in the patient's body independently of the microscope andthe sleeve. A means of coupling is preferably used which allowsadjustment of the position of the cannula relative to the microscopealong the optical axis of the microscope. This facilitates adjustment ofthe distance between the microscope objective and the lens means in thecannula to obtain proper focus at a desired distance when used withmicroscopes having a fixed focal length objective lens. In use, thecannula is usually positioned in the patient's body before coupling itto the microscope, and proper orientation of the cannula is obtained bydirect visualization of the body cavity through the optical passage.With the cannula in position, the microscope is aligned with the cannulaand the two are coupled together. Because the cannula enters into thebody cavity and may come into direct contact with tissue within the bodycavity, it is adapted for easy removal from the microscope forsterilization or disposal after use.

In addition, the visualization system may include means for illuminatingthe body cavity. The illuminating means may comprise a light sourcewhich is independent of the cannula, but, in a preferred embodiment,comprises a plurality of optical fibers fixed to the cannula andextending from its proximal end to its distal end. At the proximal end,the optical fibers may be connected to a light source so as to transmitlight into the body cavity.

In a further preferred embodiment, the cannula of the invention includesmeans for directing a fluid onto a surface of a lens positioned in thepassage of the cannula, for purposes such as removing debris ordefogging the lens. The fluid directing means may comprise, for example,a lumen extending through the cannula body, a connector at the proximalend in communication with the lumen for connection to a fluid deliverysource, and an opening at the distal end in communication with the lumenfor directing the fluid onto the surface of the lens. The fluid maycomprise a liquid such a saline solution for debris removal and/orirrigation, or a gas such as carbon dioxide for defogging ordehumidifying the lens.

The system and method of the invention offer significant advantages overprevious visualization devices for use in minimally-invasive surgery.The invention provides the high image quality, natural hand-eyecoordination and correct image orientation of direct vision, whileallowing multiple persons to view the surgical site simultaneously.Visualization is further enhanced by the stereoscopic capability of theinvention, which greatly improves depth perception. Moreover, theinvention allows the use of high-power stereo microscopes withselectable magnification to produce an exceedingly high-quality image,making the invention particularly well-adapted for visualization ofmicrosurgical procedures. Further advantages of the invention includethe ability to interchange lenses easily, the capability for wide-angleviewing, as well as the ability to introduce or withdraw surgicalinstruments, body tissue, or prostheses into or out of the body cavitywithout the need for additional incisions.

A further understanding of the nature and advantages of the inventionmay be realized by reference to the remaining portions of thespecification and the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a percutaneous visualization systemconstructed in accordance with the principles of the present invention.

FIG. 2 is a front cross-sectional view of the percutaneous visualizationsystem of FIG. 1.

FIG. 3 is a front cross-sectional view of an alternative embodiment ofthe percutaneous visualization system of the invention.

FIG. 4A is front cross-sectional view of a second alternative embodimentof the percutaneous visualization system of the invention.

FIG. 4B is a top view of the percutaneous visualization system of FIG.4A.

FIG. 5 is a perspective view of a further embodiment of the percutaneousvisualization system of the invention.

FIG. 6A is a perspective view of an obturator in the visualizationsystem of the invention.

FIG. 6B is a perspective view of the obturator of FIG. 6A positionedwithin the cannula of the visualization system of the invention.

FIG. 6C is a perspective view of a distal portion of an obturator in thevisualization system of the invention in an alternative embodimentthereof.

FIG. 7 is a perspective view of a further embodiment of thevisualization system of the invention, in which an illumination means ismounted to the cannula.

FIG. 8 is a transverse cross-section taken through line 8—8 in FIG. 7.

FIGS. 9A-9C are bottom end views of the cannula of the visualizationsystem of the invention, showing alternative configurations of theillumination means.

FIG. 10 is a perspective view of the visualization system of theinvention positioned in the chest wall of a patient, showing a firstembodiment of means for maintaining the position of the cannula relativeto the patient's body.

FIG. 11 is a perspective view of the visualization system of theinvention showing a further embodiment of the means for maintaining theposition of the cannula.

FIG. 12 is a front view of the visualization system of the inventionmounted to a surgical operating table on which a patient is shown incross-section, including a stereo-microscope supported by a floor stand.

FIG. 13 is a schematic illustration of the stereo-microscope in thevisualization system of FIG. 12.

FIG. 14 is a front cross-sectional view of the visualization system ofthe invention positioned in a body cavity of a patient, illustrating theperformance of a minimally-invasive surgical procedure.

FIG. 15 is a front view a further embodiment of a visualization systemaccording to the invention positioned in a patient's body, shown incross-section.

FIG. 16 is a front cross-sectional view of a coupling sleeve and cannulain the visualization system of FIG. 15.

FIG. 17 is a front cross-sectional view of a cannula coupled to amicroscope in a further embodiment of a visualization system accordingto the invention.

FIG. 17A is a schematic illustration of the light path through thecannula of FIG. 17.

FIGS. 18A-18B are front cross-sectional views of a visualization cannulain an additional embodiment of a visualization system according to theprinciples of the invention.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

This invention is directed to a percutaneous visualization system foruse in minimally-invasive surgical procedures, and particularly, for usein microsurgical procedures in which an extremely high-quality image ofthe surgical site is critical for success.

The invention will find use in a variety of endoscopic, thoracoscopic,laparoscopic, pelviscopic, arthroscopic, and other minimally-invasiveprocedures. The invention is particularly well-adapted, however, tofacilitate visualization within the thoracic cavity during thoracoscopicsurgery of the heart, lungs, thoracic vessels, and other thoraciccontents. For example, the visualization system of the invention may beused in conjunction with the performance of thoracoscopic coronaryartery bypass grafting (CABG) using the methods described in co-pendingapplication Ser. No. 08/023,778, the disclosure of which has beenincorporated herein by reference. As described in that application,coronary artery bypass grafting may be performed by means ofmicrosurgical instruments introduced through percutaneous cannulaepositioned in the chest wall in intercostal spaces of the rib cage.Microsurgical techniques are used to create an anastomosis, usually bysuturing, between a coronary artery and either an existing artery suchas the mammary artery, or a natural or synthetic arterial shuntconnected to an upstream arterial blood source.

A major part of the thoracoscopic CABG procedure is performed on or nearthe surface of the heart where the coronary arteries are located. Thisarea lies in the range of about two to ten centimeters below theinterior surface of the chest wall and is surrounded by the rib cage,eliminating the need for fluid distension, which is required inlaparoscopy, pelviscopy, arthroscopy, and the like. Thus, thoracoscopicCABG and other similar procedures present a unique set of considerationsfor visualization. First, from the interior of the chest wall, there isa relatively unobstructed view of the heart and other vessels in thethoracic cavity, in contrast to laparoscopy or pelviscopy, in whichvarious organs and vessels will frequently lie between the abdominalwall and the surgical site. Second, in thoracoscopic CABG procedures,the surgical site to be visualized is relatively close to the chestwall, in comparison to many common laparoscopic surgical procedures,where the surgical site may be 10 to 30 cm from the point of entrythrough the abdominal wall. Third, because there is no need for fluiddistension in thoracoscopic procedures, visualization devices need notbe adapted to prevent fluid leakage from the body cavity. Finally, themicrosurgical techniques used to perform procedures such as CABG requirean extremely high-quality, stereoscopic image of the surgical site withgood depth perception, and usually demand the ability to view the siteat wide-angle as well as magnification. This invention responds to theneed for a visualization system adapted for use under these uniqueconditions.

A first embodiment of the visualization system of the invention isillustrated in FIGS. 1 and 2. Visualization system 20 includes a cannula22 comprising a tubular cannula body 24 having a proximal end 26 and adistal end 28. A first passage 30 extends within cannula body 24 fromproximal end 26 to distal end 28. In this embodiment, first passage 30is open and unobstructed through the entire length of cannula body 24.Further, first passage 30 is tapered toward distal end 28 at a taperangle selected to allow stereoscopic visualization through cannula body24, as described more fully below. The exterior of cannula body 24 mayalso be tapered as illustrated, so as to minimize the profile of thecannula and to facilitate percutaneous introduction into a body cavity.Usually, the exterior taper of cannula body 24 will be the same as thetaper angle of first passage 30. A rim 32 may be provided about theexterior of cannula body 24 near proximal end 26, to allow for manualhandling or attachment to holding or aligning devices.

Visualization system 20 further includes, in a preferred embodiment, asleeve 34 comprising a tubular sleeve body 36 having a proximal end 38and a distal end 40. An optical passage 42 extends between proximal end38 and distal end 40. Optical passage 42 is tapered at a taper angleselected to allow stereoscopic visualization of a body cavity, asdescribed more fully below. The exterior of sleeve body 36 is configuredto allow sleeve 34 to be positioned within first passage 30 of cannula22, and usually has a taper corresponding to that of first passage 30 soas to nest therein. Sleeve body 36 may also have a rim 44 at itsproximal end 38 which seats against rim 32 of cannula 22.

The term “tubular” as used herein to describe cannula body 24 and sleevebody 36 is intended to encompass various cross-sectional shapes,including round, oval, rectangular, and the like. Further, cannula body24 and/or sleeve body 36 may not have a continuous, solid wall, butinstead may have longitudinal or circumferential slots or holes, or mayhave a cage or mesh structure with sufficient rigidity to maintain theshape and patency of first passage 30 and/or optical passage 42 whenpositioned in the wall of a body cavity.

Cannula body 24 and sleeve body 36 may be constructed of variousmaterials, including metals such as stainless steel or plastics such aspolycarbonate, or ABS. The length and transverse dimensions of cannulabody 24 and sleeve body 36 may vary according to the procedure andpatient for which they are adapted. In thoracoscopic procedures, cannulabody 24 will usually have a length between about 5 cm and 15 cm, and adiameter at distal end 28 as small as 3 mm and no larger than about 20mm in order to be positionable within an intercostal space of the ribcage. The diameter at proximal end 26 will depend upon the externaltaper (if any) of cannula body 24, and will preferably be about 10 mm to50 mm.

In a preferred embodiment, a wide-angle lens system is mounted within orin optical alignment with optical passage 42 of sleeve 34. As shown inFIG. 2, in an exemplary embodiment, a lens 46 is mounted in alignmentwith optical passage 42 at or near distal end 40 of sleeve body 36. Lens46 may be mounted directly within optical passage 42, or within atubular lens mount 48 fixed to distal end 40 of the sleeve, asillustrated. In a preferred embodiment, lens 46 is a negative-focallength lens, having at least one concave surface 50. The focal length oflens 46 will be dictated by a number of considerations, including thedistance of the site to be visualized from lens 46, and the size of thefield desired. Focal lengths in the range of −6 to −12 mm, for example,are frequently useful to facilitate visualization of a coronaryanastomosis procedure during closed-chest coronary artery bypassgrafting. Such lenses are commercially available from Melles Griot ofIrvine, Calif., Edmund Scientific Co. of Barrington, N.J., or ControlOptics of Baldwin Park, Calif. Various lens configurations and lenscombinations may be used to provide either wide-angle or magnificationcapabilities. In this way, multiple sleeves may be equipped with varioustypes of lenses, and the sleeves interchanged in first passage 30 ofcannula 22 according to the visualization capability desired.

As mentioned above, optical passage 42 and first passage 30 arepreferably configured to allow stereoscopic vision into a body cavity.The term “stereoscopic vision” as used herein is intended to refer tothe ability to see an object from two different angles. This is normallyaccomplished by a person simply looking at an object with his or her twoeyes which, because they are slightly separated, provide two differentangles of sight. Stereoscopic vision, as opposed to monoscopic vision,provides the ability to perceive depth in the object or objectsvisualized. In complex microsurgical procedures, such depth perceptioncan be of great advantage.

In order to provide for stereoscopic vision, optical passage 42 andfirst passage 30 are preferably tapered at a taper angle a selected suchthat when sleeve 34 and cannula 22 are positioned in a patient withdistal end 28 of the cannula within a body cavity, the user can lookwith both eyes through optical passage 42 from a comfortable positionover the patient and see the surgical site. Taper angle a will thereforedepend on a number of factors, including the location of the surgicalsite, the height of the user's eyes with respect to the patient, thelength and diameter of cannula 22 and sleeve 34, and the type of lens(if any) in optical passage 42. Where the visualization system isconfigured for use in thoracoscopic procedures such as CABG, taper anglea will usually be at least 5°, and preferably between 5° and 30°, wherecannula 22 and sleeve 34 each have a length between about 5 cm and 15cm. Alternatively, optical passage 42 and first passage 30 may have avery slight taper or no taper at all, but will have an inner diameterwhich is large enough and a length which is short enough to allowstereoscopic vision into the body cavity. If magnification means such asa stereo-microscope or surgical telescopes are used as described below,stereoscopic vision may be possible with little or no taper in opticalpassage 42 or first passage 30.

FIG. 3 illustrates a further embodiment of visualization system 20,wherein a lens means 52 is mounted within first passage 30 of cannula22. Lens means 52 may comprise a wide-angle lens system, such as anegative focal length lens, or a variety of other lens types, includinga simple translucent, non-refractive window. In this embodiment, thebody cavity may be visualized by looking directly through first passage30 and lens means 52, without the use of a separate sleeve for mountingthe lens as in previous embodiments.

An additional embodiment of the visualization system of the invention isillustrated in FIGS. 4A-4B. In this embodiment, cannula 22 is adaptedfor use in laparoscopic and other procedures in which the body cavity isfilled with a distension fluid such as carbon dioxide. Cannula 22includes a sealing means 54 mounted in first passage 30, usually nearproximal end 26. In an exemplary embodiment, sealing means 54 comprisesa diaphragm of a compliant material such as rubber with one or moreslits formed in a middle portion thereof. Other configurations ofsealing means 54 are also possible, such as a trumpet valve or stopcock.In this way, sleeve 34 (described above), and/or surgical instruments,prostheses, etc., may be introduced through sealing means 54 and firstpassage 30 into the body cavity without significant leakage ofdistension fluid.

Cannula 22 may further include retention means for minimizing movementof the cannula when positioned in the wall of a body cavity. In oneembodiment, illustrated in FIG. 5, the retention means comprises aplurality of ridges or bumps 56 on the exterior surface of cannula body24. Ridges 56 are shown in a helical thread pattern, which in somecircumstances may assist introduction of the cannula, as well asresisting movement once the cannula is positioned. Alternatively, ridges56 may be configured in parallel rings or in other patterns which helpto increase friction with the tissue and/or bones of the chest, abdomen,or other body cavity.

In a further embodiment, the visualization system of the inventionincludes, as shown in FIGS. 6A-6C, an obturator 58 to facilitateintroduction of cannula 22 into a body cavity. As illustrated in FIG.6A, obturator 58 comprises a middle section 60, a distal tip section 62,and a proximal end section 64. In a preferred embodiment, at least aportion of middle section 60 is tapered at an angle corresponding to thetaper angle of first passage 30 so that obturator 38 nests withincannula 22 with distal tip section 62 exposed distally of the cannula,as shown in FIG. 6B. Preferably, distal tip section 62 tapers to a pointto facilitate penetration of tissue. Alternatively, distal tip section62 may be rounded as shown in FIG. 6C, providing a blunt distal end toreduce trauma as obturator 58 and cannula 22 are urged through a smallincision into a body cavity. Obturator 58 may also have a length shortenough to prevent damaging the interior organs upon insertion.

FIGS. 7, 8, and 9A-9C illustrate additional embodiments of theinvention, wherein cannula 22 includes means for illuminating the bodycavity. In an exemplary embodiment, illustrated in FIGS. 7 and 8, theilluminating means comprises a plurality of optical fibers 66 extendinglongitudinally through a concentric passage 68 in cannula body 24 orembedded in the wall of cannula body 24. Concentric passage 68 is openat distal end 28 of cannula body 24, exposing distal ends 70 of opticalfibers 66. Optical fibers 66 are bundled together and coupled at theirproximal ends to an optical connector 72 which may be connected to alight source. In this way, light may be transmitted into the body cavitythrough optical fibers 66. In other embodiments, optical fibers 66 maybe disposed in a crescent-shaped lumen 74 as in FIG. 9A, or in one ormore non-concentric lumens 76 extending parallel to first passage 30 asin FIG. 9B.

In a further alternative embodiment, shown in FIG. 9C, cannula body 24is constructed of a light transmitting material such as acrylic orpolystyrene. A light source may be positioned near or attached toproximal end 26 of cannula 22 in order to transmit light through distalend 28 of cannula body 24 into the body cavity. Preferably, a sleeve 78is disposed about the exterior of cannula body 24 to assist lighttransmission. Sleeve 78 may have a reflective coating on its innersurface adjacent cannula body 24 to reflect light toward distal end 28,or may be of a different index of refraction, so that the sleeve acts asa single optical fiber.

The visualization system of the invention may further include means formaintaining the orientation or position of cannula 22. As illustrated inFIG. 10, in a first embodiment, the means for maintaining the positionof the cannula comprises one or more stays 80 which are attached at oneend 82 to cannula 22, usually near proximal end 26. Stays 80 may beeither a flexible material such as suture, cord, wire, or cable, or amore rigid material such as steel rod. Stays 80 have a free end 84 whichmay be secured to another structure so as to hold cannula 22 in aparticular angular orientation relative to body cavity BC. In oneembodiment, free ends 84 are taped or sutured to the patient's skin. Anattachment pad 86 may be fixed to each free end 84 for adhesive orsuture attachment to the skin. In other embodiments, free ends 84 may beclipped, tied, or otherwise attached to the surgical drapes or to asupport structure attached to the operating table (not shown), so as tomaintain cannula 22 at a particular angle.

In a second exemplary embodiment, illustrated in FIG. 11, the means formaintaining the position of cannula 22 comprises a rigid or semi-rigidsupport member 88 which may be fixed to the operating table or othersupporting structure. Means are provided for adjustably attachingcannula 22 to support member 88. In one embodiment, cannula 22 isattached to support member 88 by means of a collar 90 which clamps aboutthe cannula body 24 near its proximal end 26, preferably about rim 32.Collar 90 is pivotally attached to support member 88 by aball-and-socket joint 92, which may be locked in a particular positionby means of a set screw 94. In this way, cannula 22 may be positioned inthe body cavity and manipulated to a desired angular orientation so thatthe surgical site is visible through first passage 30. Ball-and-socketjoint 92 is then locked by tightening set screw 94, thereby maintainingcannula 22 in the desired position and freeing the user's hands toperform a surgical procedure. Other mechanisms for holding and aligningsurgical retractors and scopes may be adapted for this purpose, such asthose described in U.S. Pat. No. 5,210,742, the disclosure of which isincorporated herein by reference.

FIG. 12 illustrates a visualization system according to the inventionwhich includes magnification means aligned with first passage 30 ofcannula 22 and/or optical passage 42 of sleeve 34. In a preferredembodiment, the magnification means comprises a stereo-microscope 96suspended from a movable arm 98, which may be either floor standing asshown, or ceiling-mounted over operating table 100 on which patient P ispositioned. Cannula 22 is positioned such that its distal end 28 iswithin a body cavity of patient P, such as the thoracic cavity. Cannula22 is supported by collar 90 coupled to support arm 88, which is mountedto rails 101 on operating table 100. Sleeve 34 is positioned withincannula 22 so that its distal end 40 is within the body cavity.

Stereo-microscope 96 includes a main housing 102 and an objective lenshousing 104, which is aligned with optical passage 42 (FIG. 2) at theproximal end 38 of sleeve 34. At least one, and preferably a plurality,of binocular eyepieces 106 are mounted to housing 102, usually in amanner to allow adjustment of eyepiece height, angular disposition, andinter-eyepiece distance. Housing 102 is preferably mounted to arm 98 soas to allow rotation of stereo-microscope 96 about one or more axes.

FIG. 13 is a schematic illustration of stereo-microscope 96 inconjunction with sleeve 34 of the present invention. In one exemplaryembodiment, stereo-microscope 96 comprises an operating microscope suchas the OPMI 7 PH available from Carl Zeiss, Inc., of New York, N.Y.,which is described in detail in Hoerenz, “The Operating Microscope,”Journal of Microsurgery 1:364-369; 1:419-427; 2:22-26, 2:126-139;2:179-182 (1980), the complete disclosure of which is incorporatedherein by reference. Stereo-microscope 96 comprises an objective lens108 which is optically aligned with optical passage 42 in sleeve 34.Sleeve 34 is equipped with a wide-angle lens 46 mounted in opticalpassage 42, which receives light rays reflected from an object in planeO in the patient's body cavity. Wide angle lens 46 creates an image ofthe object on image plane I between lens 46 and the object plane. Theheight of objective lens 108 is adjusted so that image plane I issituated in the focal plane of objective lens 108. Light raystransmitted from wide-angle lens 46 through optical passage 42 arereceived by objective lens 108 and transmitted in parallel intomagnification section 110. A pair of miniature telescope systems 112 aredisposed in magnification section 110 and are configured to allow useradjustment of image magnification. Telescope systems 112 take theparallel ray image from objective lens 108 and increase or decrease itsmagnification (as adjusted by the user). The light rays leavemagnification section 110 in parallel and are transmitted into abinocular tube 114. Binocular tube 114 includes a pair of objectivelenses 116 which magnify the image of object O and transmit it to a pairof ocular lenses 118 in eyepieces 106, which may be aligned with each ofthe user's eyes E. In an exemplary configuration, with a 300 mmobjective lens 108 and 125 mm binocular tube 114, the magnification maybe varied between 3.3 (for a field of view of 60 mm diameter) and 20.8(for a field of view of 10 mm diameter).

Stereo-microscope 96 may further include one or more beam splitters 120disposed between magnification section 110 and binocular tube 114. Beamsplitter 120 allows a portion of the light rays from object O to bereflected to additional eyepieces 106 (see FIG. 12), and/or to a cameramount 122 to which a video camera 124 may be mounted. In this way,multiple observers may simultaneously view a procedure either by lookingthrough eyepieces 106 or by viewing a video monitor 126 connected tovideo camera 124.

In an alternative embodiment (not illustrated), a single, largemagnifying lens configured to be looked through with both of the user'seyes, similar to the lenses used, for example, in photographic slideviewers, is mounted to proximal end 26 of cannula body 24, or positionedin optical alignment with first passage 30 separated from cannula 22. Inthis way, stereoscopic magnification of the surgical site isaccomplished without requiring the user to align his or her eyes withthe binocular eyepieces of a microscope, and further allowing multipleobservers to look through cannula 22 simultaneously.

FIG. 14 illustrates the visualization system of the present inventionpositioned in a body cavity BC of a patient. In the figure, body cavityBC represents the thoracic cavity, but it should be understood that theinvention will be useful for visualization of procedures in various bodycavities, including the abdomen and pelvis. Body cavity BC is enclosedby a wall W, in which are disposed a plurality of ribs R of thepatient's rib cage. Ribs R are separated by intercostal spaces I, whichtypically range in width from about 5 mm to 20 mm in adult patients. Thepatient's heart H is disposed within body cavity BC, usually about 2 cmto 6 cm below the interior surface of wall W.

Cannula 22 is positioned in an intercostal space I between a pair ofribs R so that the distal end 28 of cannula 22 is within body cavity BC.Usually, an obturator (not shown in FIG. 14) is positioned in firstpassage 30 of cannula 22 to facilitate penetration of wall W duringintroduction, as described above in connection with FIGS. 6A-6C. Sleeve34 is positioned in cannula 22 so that wide-angle lens 46 is disposedwithin body cavity BC. Cannula 22 may be manipulated to a desiredangular orientation and depth, and secured in position by means of staysor a clamp, as described above with reference to FIGS. 10 and 11. Inaddition, illuminating means, either integral with cannula 22 or on anindependent device introduced through a separate incision or cannula(not shown in FIG. 14), may be utilized to transmit light into the bodycavity.

Additional trocar sleeves 130 of well-known construction are positionedin intercostal spaces I between adjacent ribs R to facilitateintroduction of surgical instruments to perform a procedure in bodycavity BC. A variety of minimally-invasive procedures may be performed,including those described in co-pending application Ser. No. 08/023,778,which has been incorporated herein by reference. The invention isparticularly well-adapted for visualization of microsurgical proceduressuch as thoracoscopic CABG, due to the invention's extremely high imagequality, its wide-angle and magnification capabilities, and itsfacilitation of direct visualization of the surgical site. For theperformance of CABG, surgical instruments 132, which may compriseforceps, scissors, needle drivers, graspers, and otherspecially-designed instruments, are introduced through one or moretrocar sleeves 130 into body cavity BC to create an arterial bloodsource, and to perform an anastomosis between the arterial blood sourceand a coronary artery on heart H.

Using the visualization system of the invention, the surgeon maydirectly and stereoscopically visualize the procedure through opticalpassage 42 in sleeve 34. Wide-angle lens 46 allows the surgeon to see alarger area in the body cavity, if desired. Sleeve 34 together withwide-angle lens 46 may be removed to substitute a different lens size ortype, or the sleeve may be left out of cannula 22 to allow directviewing with no lens. In addition, surgical instruments may beintroduced through cannula 22 to assist in the procedure. Visualizationmay be enhanced by the use of multiple cannulas positioned in variouslocations in the chest wall, as well as by using conventional endoscopicvisualization devices such as thoracoscopes positioned through trocarsleeve 130. Magnification means, such as the stereo-microscopeillustrated in FIGS. 12-13, may be positioned in alignment with opticalpassage 42 to magnify the image. Preferably, a stereo-microscope havingmultiple binocular eyepieces is utilized, to allow a plurality ofobservers to view the procedure simultaneously. Alternatively, thesurgeon may wear surgical loupes (magnifying eyeglasses) to magnify theimage viewed through optical passage 42.

Still another embodiment of the visualization system of the invention isillustrated in FIGS. 15-16. In this embodiment, as shown in FIG. 15,cannula 22 is mechanically coupled to stereomicroscope 96 by a couplingsleeve 140. In this way, first passage 30 of cannula 22 is maintained inoptical alignment with the objective lens of stereomicroscope 96, andcannula 22 is supported and maintained in a desired orientation bystereomicroscope 96, eliminating the need for a separate supportstructure, stays, or clamps.

In this embodiment, stereomicroscope 96 is preferably one which is notonly linearly positionable along three perpendicular axes, but isrotationally positionable about at least two axes to allow the objectivelens of the microscope to be aligned with cannula 22 in a variety ofangular orientations relative to body cavity BC. For example, the OPMIMD series or OPMI CS-I surgical microscopes available from Carl Zeiss,Inc. of Thornwood, N.Y., may be utilized.

A more detailed illustration of cannula 22 and coupling sleeve 140 ofthe system of FIG. 15 is seen in FIG. 16. As described above, cannula 22has a first passage 30 in which a sleeve 34 may be positioned. A lens46, usually comprising a wide-angle lens system or negative focal lengthlens, is mounted near the distal end 40 of sleeve 34. Optical fibers 66extend from optical connector 72 through a concentric lumen 68 incannula 22, such that light is transmitted through their distal ends 70to illuminate the body cavity. Optical connector 72 is connected to anoptical cable 150 which is connected to a light source.

Coupling sleeve 140 has a proximal end 142 disposed within a cylindricalbore 144 in an adaptor assembly 146 attached to stereomicroscope 96.Preferably, coupling sleeve 140 is slidable within bore 144 to allowadjustment of the position of coupling sleeve 140 relative to microscope96 along its optical axis, so that lens 46 may be optimally positionedaccording to the focal length of the microscope's objective lens.Various other types of mechanisms may be used to facilitate positionaladjustment of coupling sleeve 140, including a rack and pinion orhelical threads on coupling sleeve 140. Set screws 147 engage couplingsleeve 140 to hold it in position. An axial passage 149 extends betweenproximal end 142 and distal end 148.

Distal end 148 of coupling sleeve 140 is attached to proximal end 26 ofcannula 22 by set screws, adhesive bond, band clamp, or other knownmeans. In one embodiment, cannula 22 is attached to coupling sleeve 140such that it may be easily decoupled therefrom to allow cannula 22 to beindependently introduced into the body cavity and oriented by directvision through optical passage 42, after which microscope 96 may bealigned with cannula 22 and coupling sleeve 140 reattached to thecannula. The ability to quickly decouple cannula 22 from coupling sleeve140 also allows cannula 22 to be removed from microscope 96 after usefor disposal or sterilization.

To facilitate interchanging sleeves 42 having various types of lenses46, a window 152 is disposed on a lateral side of coupling sleeve 140.In this way, sleeve 34 may be grasped near its proximal end 38 byreaching one or more fingers through window 152. Sleeve 34 may thus beremoved from first passage 30 for replacement with an alternate sleevehaving a different type of lens, or, if visualization is compromised bydebris or humidity, for replacement with a clean or defogged lens.

In use, cannula 22 is first decoupled from stereomicroscope 96 andpositioned at the desired location on patient P. Cannula 22 ispercutaneously introduced through a small incision or puncture so thatits distal end 28 is within body cavity BC. The angular orientation ofcannula 22 may be adjusted by looking directly through optical passage34 to observe the contents of body cavity BC and by manipulating cannula22 until the desired site in body cavity BC is aligned with opticalpassage 34. Stereomicroscope 96 is then positioned so that its objectivelens is optically aligned with optical passage 34, and coupling sleeve140 is attached to the proximal end 26 of cannula 22. Further positionaladjustment may be accomplished by manipulating stereomicroscope 96 whilecannula 22 remains coupled to coupling sleeve 140.

Cannula 22 and sleeve 34 in the embodiments described above may be madeof any of a variety of biocompatible materials. However, because thesecomponents may penetrate into a body cavity and come into contact withliving tissue, they must be sterile. Therefore, cannula 22 and sleeve 34are preferably constructed of a material which may be sterilized betweenuses, or which is disposable after each use. Sterilizable materialssuitable for cannula 22 and/or sleeve 34 include stainless steel,anodized aluminum, and other biocompatible metals. Materials which havethe necessary performance characteristics yet which are of sufficientlylow cost to be disposable include plastics such as polycarbonate,acetonitrile butyl styrene (ABS), or polyvinyl chloride (PVC).

Yet another embodiment of the visualization system of the invention isillustrated in FIG. 17. In this embodiment, an adaptor assembly 146 ismounted to a stereomicroscope in the manner described above inconnection with FIGS. 15-16. A tubular cannula 160 has a proximal end162 slidably disposed within passage 144 and held by set screws 147.Cannula 160 has a distal end 164 configured for percutaneousintroduction into a body cavity through a body wall W, usually having amaximum width or diameter which is less than about 20 mm, preferablyabout 5 mm-10 mm, so as to pass through an intercostal space of the ribcage. An optical passage 166 extends between proximal end 162 and distalend 164, having a tapered proximal section 168 and a non-tapered distalsection 170.

In a preferred embodiment, a lens system is mounted within opticalpassage 166 to facilitate visualization of a field within the bodycavity which is significantly larger than the transverse cross-sectionalarea of cannula 160 at distal end 164. In an exemplary configuration, adouble concave negative focal length lens 172 is disposed in distalsection 170 of optical passage 166 near distal end 164. A first achromat173 is mounted proximally of lens 172, and an aperture or iris 174 isdisposed proximally of achromat 173. Second, third, fourth, fifth, andsixth achromats 175, 176, 177, 178, 179 are disposed serially withindistal section 170 proximal to iris 174. A larger achromat 180 ismounted within optical passage 166 near the proximal end of proximalsection 168.

Preferably, cannula 160 and the lens system within optical passage 166is configured to pass through a trocar sleeve 183 having an innerdiameter of 12 mm or smaller (113 mm² transverse cross-sectional area)while providing a field of view of between 5° and 90°, preferably about20°-60°, off of the optical axis defined by optical passage 166. Thiswill allow visualization of a field within the body cavity of at leastabout 30 mm diameter (707 mm² area), and preferably about 50-60 mmdiameter (1963 mm²-2827 mm² area), at a distance of between 20 mm and 80mm, preferably around 30 mm to 60 mm, from distal end 164. In addition,the lens system should provide an image situated at the focal length ofthe microscope's objective lens which is within the field of view of aconventional surgical microscope. For example, a conventional surgicalmicroscope with 5-25× magnification and a 175 mm objective lens may havea field of view between 6 mm and 28 mm in diameter (depending uponmagnification).

Although a variety of lens combinations are possible in cannula 160, inan exemplary embodiment, double concave lens 172 has a focal length of−6 mm, achromats 173, 177 each have a focal length of 35 mm, achromats175, 176, 178, 179 have a focal length of 12.5 mm, and achromat 180 hasa focal length of 150 mm. All of the lenses in distal section 170 ofoptical passage 166 have a diameter of 6.25 mm, while achromat 180 has adiameter of 30 mm. Iris 174 may have various radii depending upon thedepth of field desired, as is usually between about 0.50 mm and 1.25 mm,for a working F number between 56 and 22. Achromats 173, 175, 176, 177,178, 179, 180 are of conventional construction, consisting of twooptical components of different densities bonded together so as tocorrect chromatic aberrations that can occur from the diffractioneffects of a lens of a single type of glass. Such achromats areavailable from, for example, Edmund Scientific Co. of Barrington, N.J.

The light path resulting from the foregoing lens system is illustratedin FIG. 17A. For lenses 172-179 of diameter D1 of 6.25 mm, and achromat180 of diameter D2 of 30 mm, a field of diameter F up to about 60 mm isvisible, and an image of diameter I of about 28 mm is provided forviewing by the microscope at the focal length of its objective lens.This image is then magnified by, e.g., 5×-25× by the microscopeobjective, and split into separate paths for stereoscopic viewing bymeans of a binocular eyepiece (see FIGS. 13 and 15).

In this way, cannula 160 may be non-tapered, may have a smallerdiameter, and may have a greater length than previous embodiments whilestill providing stereoscopic wide-angle visualization into the bodycavity through a small percutaneous penetration. Conveniently, cannula160 may be percutaneously introduced directly into the body cavitythrough a small incision or puncture, or through a standard trocarsleeve or other access cannula 183, which may be a Thoracoport™available from United States Surgical Corporation of Norwalk, Conn.

Cannula 160 is further provided with means for illuminating the bodycavity, which may comprise a plurality of optical fibers 184 disposed inan annular passage 186 so that light is transmitted through their distalends 188 into the body cavity. Optical fibers 184 are connected to anoptical connector 190 for connection to a light source. Alternatively,all or a portion of cannula 160 may be constructed of a light conductivematerial such as acrylic to form a light pipe to transmit light into thebody cavity.

It will be understood to those of skill in the art that, as analternative to mounting cannula 160 to a conventional surgicalmicroscope, the lens system of cannula 160 along with the objectivelens, telescope systems, eyepieces and other optics of the microscopemay be mounted into a single body or frame to create an integrateddevice which is more compact and portable.

In an alternative embodiment, a distal portion of cannula 160 may beconfigured to allow viewing from an angle of, e.g., 45°-90° relative tothe axial direction as defined by the proximal portion of opticalpassage 166 to facilitate viewing portions of the body cavity lateral tothe puncture through which cannula 160 is introduced. A reflecting prismmay be mounted in optical passage 166 near distal end 164 to reflectlight from the distal end 164 toward the proximal portions of opticalpassage 166. An optical design like that used in commercially-availableangled endoscopes such as the Olympus 45° endoscope (Catalog No. A5256)available from Olympus Corp., Medical Instruments Division, LakeSuccess, N.Y., may be utilized. In another embodiment (not illustrated),cannula 160 has a steerable distal end which may be deflected into avariety of angles within the body cavity by manipulating a steering wireor other actuation mechanism extending from distal end 164 to a locationoutside of the body cavity.

FIGS. 18A-18B illustrate a further embodiment of a visualization systemaccording to the invention, wherein cannula 22 is provided with meansfor delivering a fluid into the body cavity to enhance visualization.Such fluid delivery may accomplish various purposes, includingirrigation of a site to be visualized, removal of debris from lens 46,or dehumidifying or defogging lens 46. In a first embodiment, shown inFIG. 18A, a delivery tube 196 is fixed to the exterior of cannula 22 andhas a distal end 198 disposed near distal end 24 of cannula 22, and aproximal end 200 having a hose barb 202 or other connector configuredfor connection to a fluid delivery source. A lumen 204 extends fromproximal end 200 to distal end 198, and is in communication with anopening 206 at distal end 198. In a preferred embodiment, opening 206 ispositioned so as to direct a fluid onto the distal surface of lens 46.In this way, a gas such as carbon dioxide or air can be directed towardthe surface of the lens to dry the lens surface and keep it free of fog.Alternatively, a liquid such as saline can be delivered to remove debrison lens 46 and/or cannula 22 which may be obstructing vision, or toirrigate a site in the body cavity.

Rather than being fixed to cannula 22, delivery tube 196 may be slidablycoupled to cannula 22 to allow delivery tube 196 to be introduced orremoved from the body cavity as desired. For example, rings or channelsmay be provided on the exterior surface of cannula 22 through whichdelivery tube 196 may be inserted and advanced distally until its distalopening 206 is aligned with lens 46.

FIG. 18B illustrates an alternative configuration wherein one or morefluid delivery lumens 208 are formed in the wall of cannula 22, eachfluid delivery lumen 208 being connected by a manifold 210 to a hosebarb 212 or other means for connection to a fluid delivery source. Eachfluid delivery lumen 208 has an opening 214 at its distal end positionedto direct fluid toward the distal surface of lens 46. A plurality ofindividual delivery lumens 208 may be arranged circumferentially aboutcannula 22, or a single concentric delivery lumen 208 may be used with aplurality of openings 214 near distal end 24.

Cannula 22 of FIGS. 18A-18B may further be provided with lighttransmission means for lighting the body cavity. Cannula 22 may beitself constructed of a light transmitting material such as acrylic orpolystyrene, or optical fibers may be mounted to or embedded in the wallof cannula 22 and connected to an external light source to transmitlight into the body cavity, as described with reference to FIGS. 7, 8,and 9A-9C above.

While the above is a complete description of the preferred embodimentsof the invention, various alternatives, modifications, and equivalentsmay be used. Therefore, the above description should not be taken aslimiting the scope of the invention, which is defined by the appendedclaims.

What is claimed is:
 1. A surgical microscope comprising a microscopebody, lens means attached to the microscope body for magnifying anobject image, an eyepiece attached to the microscope body for viewingthe magnified object image, and coupling means attached to themicroscope body for retaining a supplementary lens in optical alignmentwith the lens means, the coupling means being configured for introducingthe supplementary lens through a percutaneous penetration into a bodycavity, wherein the coupling means comprises a sleeve having an interiorin which the supplementary lens is positioned, the sleeve having anaperture in a side thereof in communication with the interior tofacilitate interchanging the supplementary lens with other lenseswithout decoupling the sleeve from the lens means.
 2. A surgicalmicroscope comprising a microscope body, lens means attached to themicroscope body for magnifying an object image, an eyepiece attached tothe microscope body for viewing the magnified object image, and couplingmeans attached to the microscope body for retaining a supplementary lensin optical alignment with the lens means, the coupling means beingconfigured for introducing the supplementary lens through a percutaneouspenetration into a body cavity and allowing the supplementary lens to beinterchanged with an alternate lens without moving the microscope body.3. A surgical microscope comprising a microscope body, lens meansattached to the microscope body for magnifying an object image, aneyepiece attached to the microscope body for viewing the magnifiedobject image, and coupling means attached to the microscope body forretaining a supplementary lens in optical alignment with the lens means,the coupling means comprising a cannula having a passage in which thesupplementary lens may be removably positioned, the cannula having adistal end configured for introduction into the body cavity through apercutaneous penetration, the coupling means being configured forintroducing the supplementary lens through a percutaneous penetrationinto a body cavity.
 4. The surgical microscope of claim 3 wherein thecoupling means further comprises a sleeve disposed within the cannula.5. The surgical microscope of claim 4 wherein the cannula is configuredfor positioning within an intercostal space between two adjacent ribs.6. The surgical microscope of claim 5 wherein the cannula has atransverse width or diameter of less than about 20 mm.
 7. A surgicalmicroscope comprising a microscope body, lens means attached to themicroscope body for magnifying an object image, an eyepiece attached tothe microscope body for viewing the magnified object image, and couplingmeans attached to the microscope body for retaining a supplementary lensin optical alignment with the lens means, the coupling means beingconfigured for introducing the supplementary lens through a percutaneouspenetration into a body cavity, the coupling means comprising a sleevehaving an interior in which the supplementary lens is positioned, thesleeve having an aperture in a side thereof in communication with theinterior to facilitate interchanging the supplementary lens with atleast one other lens without decoupling the sleeve from the lens means.